Biological control of Himalayan Balsam

June 16th 2016

We have written quite a bit about the Japanese Knotweed Psyllid (aphalara itadori), which has been released in to the wild in the UK as a form of Japanese knotweed controland. I also wrote recently about the form of leaf spot fungus which is under research by CABI for potential release as another bio-control agent.

CABI are also experimenting with bio-control for a number of other invasive species, including Himalayan Balsam. CABI’s website gives the following information:

“In 2010, the project secured export of live specimens into our quarantine facility in the UK. We are currently researching the host range and infection parameters of the most damaging agent found attacking Himalayan balsam populations, an autoecious rust pathogen; a Puccinia species. This highly damaging potential agent attacks the stem and leaves of the plant often killing the young seedlings and reducing the photosynthetic rate of older plants during the dispersal phase of the pathogen. “

“The Himalayan balsam project is going very well and the rust we are working with is highly host specific to Himalayan balsam. As a biocontrol agent I think it’s a very interesting agent as it hits the plant twice, once when the plant is a seedling and again on the foliage of more mature plants. As for timescale of release – this would be a difficult one to answer with any certainty. As you know we need to complete the research and then submit the dossier to Fera and Defra. However, I would like to think that potentially we could have something ready for 2013 or 2014.

Any biocontrol agent will not eradicate the population but more control the species, reducing the spread. I think that the rust would highly impact on populations reducing population over time and indeed killing individuals within the population making manual and chemical control of this species easier – especially on a catchment scale. The rust would also reduce the amount of seed set of infected plants thereby reducing the next seasons population.”

As usual, we welcome this news on one hand, whilst on the other always having the nagging doubt about introducing more non-native species in to the UK. We know CABI are working very hard and are extremely diligent in their testing – and we are genuinely enthusiastic about measures that will reduce the impact of these non-native plants on our homes, rivers and countryside.

So, thanks very much to Rob and all of his team – and we hope to see a successful release of the rust fungus in the wild in due course.